In this case, the height was set roughly by the viewing height of the TV, the width by the wall it's going against (~5'-5") and it must hold the various electronics we need to serve our media needs. It also needs to have at least one drawer for the remotes and other little accessories. It would be nice to have as much storage as possible for music CD's, games, DVD's whatever. Electronics seem to be intended to fit in a 18" wide space. At least none of the things I have now is any bigger than that. And some of them need good ventilation.
I like Sketchup for visualizing designs in 3D. It's good for figuring out how the joinery might go together, as well.
|A Sketchup rendering of the nearly-final design|
It's basically three 18" wide segments. Open cubbies above and concealed storage below. Drawers on the outer sections, and a cupboard in the center. Since I wanted to use mechanical sliders on the storage drawers to take the weight, I wound up building a sort of plywood carcase inside of a traditional frame and panel construction. Or maybe I'm just decorating a plywood box with a lot of quarter-sawn white oak.
I've been burned by a few things that looked good on the computer, and then just didn't translate into reality, so I've started making full-size drawings. For something this big, I did it on a piece of brown construction paper. Go buy a roll. It's cheap, and you can use it for all sorts of stuff, from a painter's drop cloth to floor protection to art media. Anyway, here's what the full size drawing looked like, once it hung it up on the existing tv stand so we could see what it would look like in the actual space. The pencil lines are a bit tough to see in the photo. I cut a leg blank (on the left) at this stage, to see how the mass worked with the design.